/*
 * Copyright (c) 2007-2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: FuncLast.java,v 1.2.4.1 2005/09/14 20:18:43 jeffsuttor Exp $
 */
package com.sun.org.apache.xpath.internal.functions;

import com.sun.org.apache.xml.internal.dtm.DTMIterator;
import com.sun.org.apache.xpath.internal.XPathContext;
import com.sun.org.apache.xpath.internal.axes.SubContextList;
import com.sun.org.apache.xpath.internal.compiler.Compiler;
import com.sun.org.apache.xpath.internal.objects.XNumber;
import com.sun.org.apache.xpath.internal.objects.XObject;

/**
 * Execute the Last() function.
 * @xsl.usage advanced
 */
public class FuncLast extends Function {
    static final long serialVersionUID = 9205812403085432943L;

    private boolean m_isTopLevel;

    /**
     * Figure out if we're executing a toplevel expression.
     * If so, we can't be inside of a predicate.
     */
    public void postCompileStep(Compiler compiler) {
        m_isTopLevel = compiler.getLocationPathDepth() == -1;
    }

    /**
     * Get the position in the current context node list.
     *
     * @param xctxt non-null reference to XPath runtime context.
     *
     * @return The number of nodes in the list.
     *
     * @throws javax.xml.transform.TransformerException
     */
    public int getCountOfContextNodeList(XPathContext xctxt) throws javax.xml.transform.TransformerException {

        // assert(null != m_contextNodeList, "m_contextNodeList must be non-null");
        // If we're in a predicate, then this will return non-null.
        SubContextList iter = m_isTopLevel ? null : xctxt.getSubContextList();

        // System.out.println("iter: "+iter);
        if (null != iter)
            return iter.getLastPos(xctxt);

        DTMIterator cnl = xctxt.getContextNodeList();
        int count;
        if (null != cnl) {
            count = cnl.getLength();
            // System.out.println("count: "+count);
        } else
            count = 0;
        return count;
    }

    /**
     * Execute the function.  The function must return
     * a valid object.
     * @param xctxt The current execution context.
     * @return A valid XObject.
     *
     * @throws javax.xml.transform.TransformerException
     */
    public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException {
        XNumber xnum = new XNumber((double) getCountOfContextNodeList(xctxt));
        // System.out.println("last: "+xnum.num());
        return xnum;
    }

    /**
     * No arguments to process, so this does nothing.
     */
    public void fixupVariables(java.util.Vector vars, int globalsSize) {
        // no-op
    }

}
